dial up accessible PLC + HMI selection for SCR Rectifier controls

[KrisPLC]

I am looking to cost effectively upgrade old analog controls to PLC+HMI hardware for SCR controlled rectifiers. There are 100+ units in the field, usually outdoors in NEMA 4X enclosures.

The operation is as follows:
Analog Inputs: 1-4 x References (-5 to 5V, high input impedence), 1 x shunt to monitor current (0-150mV), 1 x to monitor output voltageDC V (0-12 V can be stepped down if required), 2 x RTD inputs for enclosure/SCR temperature.
Analog Output: PID controlled Process output to SCR trigger module (0-5 or 10 V or 4-20 mA).
Relay/Digital Outputs: to drive fans, status LED, etc.

PID control using reference AI as feedback to drive AO, 0-100%.
Control of rectifier operation, fans, high temp shutoff, voltage or current limits, etc
Local HMI to view data, change set point of reference target, view errors
Logging of data;
Display of data and operator adjustment of reference set point on local HMI
Must be able to connect via phone line or internet (depending on site) to view live data and download datalogs
Linking multiple rectifiers at one site would be ideal; so I would connect to one "master" to download and view all the data

So far, my frontrunner is a Micrologix 1100 ($680 USD) and 2711R-T4T, Panelview 800 display ($407), with a 2 channel AI, 2 channel AO module ($391), and an Advantech ADAM-4019+ universal input card ($361) for the high input AI (20 mOhm) and RTD inputs. I hope this works!

I am unsure what the best method is for phone line access, and datalogging.

I am looking at options from Advantech, Red Lion, and Automation Direct, but they either cost more or have technical constraints.

 

[Firejo]

I’d bring the internet to both locations and setup a VPN. Analog phone lines are going away and being replaced with internet connectivity (IP phones, etc…).

 

[KrisPLC]

Can't do that, there are 50+ client sites, a lot of security hoops that they can't or don't want to go through. Phone line is a must.

 

[Saffa]

Funny that people think that phone lines are less of a risk than Internet connectivity. Whilst it's less common these days, I'm sure there are still war-diallers out there. With a modem on a PLC serial port, there's really very little way to add any security.

If you're going to have multiple units on a site, then networking them together and having one as a master makes sense. Look into the E*W**O**N (remove stars, site censors it!) range of cellular routers. Easy to create a VPN and no need for the clients IT department to get involved. Moxa also do cellular options.

For PLC take a look at Unitronics. They do some good PLC+HMI options.

 

[Jacob.Colegrove]

IP over Cellular is your best bet. Better security and better connection speeds. You can get a private network from the cellular carrier in addition to a VPN. Red Lion also provided cellular routers with VPN capability.

If must use a phone line you have two options. (1) Serial (RS232) with a standard land-line modem. (2) IP over a Land-line using a land-line modem IP bridge.

 

[KrisPLC]

Thanks, the E**W*O*N units look good for dial up applications (but you're all correct, GSM is a better option; a lot of GSM options). Either way, remote communication does not look to be an issue.

So looking for suitable, cost effective PLC + HMI combos that do datalogging, and remote viewing (preferably via web server) is my main goal.

Allen Bradley: Micrologix 1100 + 4" Panelview 800 HMI (frontrunner)
Unitronics: PLC/HMI combo V350 looks good... looking into it. Webserver, really cheap, datalogging with SD card...
IDEC: MicroSmart. Looking into it...
Automation Direct: Looking into it...

Any other suggestions or thoughts on the above are much appreciated!

 

[Cody]

Look at www.softplc.com. They have a low cost Micro, but their Smart SoftPLC has an option for a built-in phone modem for the installations where you need dial-up. It can do all you need, with a number of I/O options (their own, ADAM, or others).

You could have the same logic and I/O solution for both dial-up and cell installations, but use a different model CPU based on the comms required. Or, just use the Smart SoftPLC for all installations.

The PLC does data logging, email/text messages, embedded web server for virtual HMI and they have VPN solutions.

 

[KrisPLC]

Cody, looked into SmartPLC, seems pricy compared to others (as per their store, it starts at $795).

Right now, I am leaning toward a Horner XLT or XL4 series. My technical guru says that he can convert a PWM output signal into an analog output using a filter, which would allow me to go for a lower model without AO.

My reasoning for choosing Horner over others (Unitronics was close):
- Wider temperature range for default models (-10 to 60 vs 0 to 50 for Unitronics).
- All the com options I need are included; CsCAN for local network, serial for remote I/O, and serial to connect to modem or Ethernet/PSTN module. Can view/edit program on master slave, view HMI, download data without a problem.

I am debating whether going with the XL4 or XLT series; I may go with both depending on application, since the XL4 is the same price as XLT+ethernet module.